U.S. patent number 10,032,550 [Application Number 15/474,638] was granted by the patent office on 2018-07-24 for moving-coil haptic actuator for electronic devices.
This patent grant is currently assigned to APPLE INC.. The grantee listed for this patent is Apple Inc.. Invention is credited to Richard H. Koch, Zhipeng Zhang.
United States Patent |
10,032,550 |
Zhang , et al. |
July 24, 2018 |
Moving-coil haptic actuator for electronic devices
Abstract
A haptic actuator features magnets coupled to an enclosure and a
movable mass with a conduction loop coupled to the enclosure via
one or more movement elastic members. One or more conduction
elastic members may be used to transmit signals to the conduction
loop to cause the movable mass to move bilinearly relative to the
enclosure and the magnets. The magnets may consist of a Halbach
array to direct magnetic flux toward the conduction loop and away
from other device components. Ferrofluid may be included between
one or more of the magnets and the conduction loop to act as a
damper in the system to improve haptic feedback. Closed loop
control, such as back EMF, capacitive sensing, and magnetic
sensing, may be included to improve system response.
Inventors: |
Zhang; Zhipeng (Santa Clara,
CA), Koch; Richard H. (Cupertino, CA) |
Applicant: |
Name |
City |
State |
Country |
Type |
Apple Inc. |
Cupertino |
CA |
US |
|
|
Assignee: |
APPLE INC. (Cupertino,
CA)
|
Family
ID: |
62874108 |
Appl.
No.: |
15/474,638 |
Filed: |
March 30, 2017 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H01F
7/066 (20130101); H01F 7/1646 (20130101); G06F
3/016 (20130101); H01F 7/064 (20130101); H01F
2007/185 (20130101) |
Current International
Class: |
G06F
1/16 (20060101); H05K 5/00 (20060101); H05K
7/00 (20060101); H01F 7/16 (20060101); H01F
7/02 (20060101) |
Field of
Search: |
;361/679.55,679.56,679.21-679.3 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Haughton; Anthony
Attorney, Agent or Firm: Brownstein Hyatt Farber Schreck,
LLP
Claims
What is claimed is:
1. An electronic device comprising: a device casing; a display
coupled to the device casing; an actuator coupled to the device
casing and for providing haptic feedback through the device casing,
the actuator comprising: an enclosure that forms an interior
volume; a magnet attached to the enclosure, the magnet configured
to generate a first magnetic field in the interior volume; a
movable mass disposed in the interior volume, the movable mass
configured to oscillate within the interior volume along a
longitudinal axis of the enclosure; a conduction loop affixed to
the movable mass and operative to generate a second magnetic field
in response to an electromagnetic signal; a movement elastic member
disposed between the movable mass and the enclosure and configured
to exert a force on the movable mass, the force varying with a
position of the movable mass; and a conduction elastic member
coupled to the enclosure and the conduction loop, the conduction
elastic member configured to convey the electromagnetic signal; and
a controller coupled to the conduction loop by the conduction
elastic member and configured to initiate the electromagnetic
signal to the conduction loop.
2. The electronic device of claim 1, wherein: the magnet is a first
magnet; the movement elastic member is a first movement elastic
member; the conduction elastic member is a first conduction elastic
member; and the actuator further comprises: a second magnet
attached to the enclosure, the movable mass located between the
first magnet and the second magnet, the second magnet configured to
generate a third magnetic field in the interior volume; a second
conduction elastic member coupled to the enclosure and the
conduction loop; a first contact attached to the enclosure and the
first conduction elastic member, the first contact configured to
constrain an end of the first conduction elastic member; a second
contact attached to the enclosure and the second conduction elastic
member, the second contact configured to constrain an end of the
second conduction elastic member; a second movement elastic member
disposed between the movable mass and the enclosure; further
wherein: the first movement elastic member is a first flexure
spring connected to a first connection location of the movable
mass, the first connection location offset from the longitudinal
axis in a first direction; the second movement elastic member is a
second flexure spring connected to a second connection location of
the movable mass, the second connection location offset from the
longitudinal axis in a second direction, the second direction
different from the first direction; the first conduction elastic
member is a first beehive spring connected to a third connection
location of the movable mass, the third connection location offset
from the longitudinal axis; the second conduction elastic member is
a second beehive spring connected to a fourth connection location
of the movable mass, the fourth connection location offset from the
longitudinal axis; the conduction loop comprises two rounded
rectangular coils; and the first and second conduction elastic
members expand and contract as the movable mass moves.
3. The electronic device of claim 1, wherein the magnet comprises a
Halbach array.
4. The electronic device of claim 1, wherein the movable mass
comprises a first portion disposed within a second portion, the
first portion thinner than a second portion.
5. The electronic device of claim 1, wherein the movement elastic
member has a spring force between 0.5 and 3 N/mm.
6. The electronic device of claim 5, wherein the conduction elastic
member has a spring force between 0.001-0.01 N/mm.
7. The electronic device of claim 1, wherein the actuator further
comprises a ferrofluid disposed between the first magnet and the
movable mass.
8. An actuator for providing haptic feedback in an electronic
device, the actuator comprising: an enclosure defining a first side
and a second side opposite the first side; a first magnet coupled
to the first side of the enclosure; a second magnet coupled to the
second side of the enclosure; a movable mass disposed between the
first and second magnets; a conduction loop connected to the
movable mass; a first movement elastic member attached to the
enclosure and to a first connection location of the movable mass; a
second movement elastic member attached to the enclosure and to a
second connection location of the movable mass; and a conduction
elastic member physically coupled to the enclosure and to the
movable mass, the conduction elastic member electrically coupled to
the conduction loop.
9. The actuator of claim 8, wherein the first and second movement
elastic members comprise at least one of a flexure spring, a leaf
spring, or a coil spring.
10. The actuator of claim 8, wherein a reaction force of the
movement elastic member is between 100 and 1000 times greater than
a spring force of the conduction elastic member.
11. The actuator of claim 8, wherein a density of the movable mass
is greater than 15 grams per cubic centimeter.
12. The actuator of claim 8, wherein: the conduction elastic member
is a first conduction elastic member; and the actuator further
comprises: a second conduction elastic member coupled to the
enclosure and the movable mass; wherein the second conduction
elastic member is electrically coupled to the conduction loop.
13. The actuator of claim 12, wherein: the enclosure has a
longitudinal axis; the first connection location is offset from the
longitudinal axis in a first direction; and the second connection
location is offset from the longitudinal axis in a second
direction, the second direction different from the first
direction.
14. The actuator of claim 13, wherein: the first conduction elastic
member is connected to a third connection location of the movable
mass, the third connection location offset from the longitudinal
axis in a third direction, the third direction different from the
first direction; and the second conduction elastic member is
connected to a fourth connection location of the movable mass, the
fourth connection location offset from the longitudinal axis in a
fourth direction, the fourth direction different from the second
direction.
15. The actuator of claim 8, wherein the conduction elastic member
is one of a flexure spring, a leaf spring, or a coil spring.
16. A method for operating an actuator to provide haptic output to
an electronic device, the method comprising: transmitting a drive
signal to a conduction loop of the actuator, thereby causing the
conduction loop and a movable body within the actuator to
oscillate; receiving, at a controller, feedback data indicating a
position of the movable body within an enclosure of the actuator;
generating, by the controller and based on the feedback data, a
signal for providing a haptic output via the actuator; transmitting
the signal to the conduction loop; receiving second feedback data
indicating a second position of the movable body; and verifying,
with the second feedback data, that the haptic output matches a
desired haptic output.
17. The method of claim 16, wherein verifying that the haptic
output matches the desired haptic output using the second feedback
data comprises comparing at least one of a determined position, a
determined velocity, or a determined acceleration with one or more
expected values.
18. The method of claim 16, wherein the drive signal generates, by
the conduction loop, a magnetic field that interacts with one or
more additional magnetic fields, thereby causing the movable body
within the actuator to oscillate.
19. The method of claim 16, wherein the second position of the
movable body indicates unwanted motion of the movable body.
20. The method of claim 19, further comprising: generating a
corrective signal to mitigate the unwanted motion of the movable
body; and transmitting the signal to the conduction loop.
Description
FIELD
Embodiments described herein relate to electronic devices, and in
particular, to electronic devices that incorporate a haptic
feedback system to provide haptic output to a user.
BACKGROUND
An electronic device can include a mechanical actuator to generate
tactile sensations for a user, generally referred to as "haptic
output." Mechanical output from the actuator can inform the user of
a specific mode, operation, or state of the electronic device, or
for any other suitable purpose. Such actuators, together with
associated electronic circuitry, can be referred to as "haptic
output components."
Some haptic output components are linear actuators that include an
enclosure, a conductive coil coupled to the enclosure, and a
movable mass that includes a magnet that is operable to move
relative to the enclosure and the coil when a current is applied to
the coil. This contributes to undesirable magnetic interference
between the moving magnets and other components of the electronic
device.
SUMMARY
Certain embodiments described herein relate to, include, or take
the form of an electronic device including: a device casing, a
display coupled to the device casing, an actuator, and a
controller. The actuator is coupled to the device casing and
provides haptic feedback at the electronic device. The actuator
includes an enclosure that forms an interior volume. A magnet is
attached to the enclosure and may be configured to generate a first
magnetic field in the interior volume. A movable mass is disposed
in the interior volume of the enclosure. The movable mass is
configured to oscillate within the interior volume along a
longitudinal axis of the enclosure. The actuator further includes a
conduction loop affixed to the movable mass and operative to
generate a second magnetic field responsive to an electrical
current. The actuator further includes a movement elastic member
between the movable mass and the enclosure. The movement elastic
member is configured to exert a force which varies with a position
of the movable mass. The actuator further includes a conduction
elastic member coupled to the enclosure and the conduction loop and
configured to convey an electromagnetic signal. The controller is
coupled to the conduction loop by the conduction elastic member and
is configured to send the electromagnetic signal to the conduction
loop.
Other embodiments described generally reference an actuator for
providing haptic feedback in an electronic device. The actuator
includes an enclosure defining a first side and a second side
opposite the first side, a first magnet coupled to the first side
of the enclosure, a second magnet coupled to the second side of the
enclosure opposite the first side, a movable mass disposed between
the first and second magnets, and a conduction loop connected to
the movable mass. The actuator further includes a first movement
elastic member attached to the enclosure and a first connection
location of the movable mass and a second movement elastic member
attached to the enclosure and a second connection location of the
movable mass. The actuator further includes a conduction elastic
member coupled to the enclosure and the movable mass. The
conduction elastic member is electrically coupled to the conduction
loop.
Still further embodiments described herein generally reference a
method for operating a controller for an actuator for providing
haptic feedback to an electronic device including the operations of
transmitting a drive signal to a conduction loop of an actuator
that causes a movable body within the actuator to oscillate,
receiving feedback data indicating a position of a movable body
within the actuator, generating a signal for providing a haptic
output based on the feedback data, transmitting the signal to the
conduction loop, receiving second feedback data indicating a second
position of the movable body, and verifying that the haptic output
matches a desired haptic output using the second feedback data.
BRIEF DESCRIPTION OF THE DRAWINGS
Reference will now be made to representative embodiments
illustrated in the accompanying figures. It should be understood
that the following descriptions are not intended to limit this
disclosure to one preferred embodiment. To the contrary, the
disclosure provided herein is intended to cover alternatives,
modifications, and equivalents as may be included within the spirit
and scope of the described embodiments, and as defined by the
appended claims.
FIG. 1 illustrates an example electronic device that may
incorporate a haptic feedback system according to one or more
embodiments presented herein.
FIG. 2 is a simplified system diagram depicting selected components
of a haptic feedback system according to one example
embodiment.
FIG. 3A depicts an example haptic actuator, such as described
herein.
FIG. 3B is a cross-section of the haptic actuator of FIG. 3A, taken
through section line A-A of FIG. 3A.
FIG. 3C is a cross-section of the haptic actuator of FIG. 3A, taken
through section line B-B of FIG. 3B.
FIG. 4A depicts a second example haptic actuator, such as described
herein.
FIG. 4B is a cross-section of the haptic actuator of FIG. 4A, taken
through section line C-C of FIG. 4A.
FIG. 4C is a cross-section of the haptic actuator of FIG. 4A, taken
through section line D-D of FIG. 4B.
FIGS. 5A-5H depict example configurations for magnet arrays in
haptic actuators, such as those described herein.
FIGS. 6A-6C depict an example configuration for capacitive sensors
within a haptic actuator, such as described herein.
FIGS. 7A-7C depict example configurations for magnetic sensors
within a haptic actuator such as those described herein.
FIGS. 8A-8C are cross-sections similar showing portions of example
haptic actuators, such as those described herein.
FIG. 9 is a simplified flow chart depicting example operations of a
haptic feedback system, such as described herein.
The use of the same or similar reference numerals in different
figures indicates similar, related, or identical items.
Additionally, it should be understood that the proportions and
dimensions (either relative or absolute) of the various features
and elements (and collections and groupings thereof) and the
boundaries, separations, and positional relationships presented
therebetween, are provided in the accompanying figures merely to
facilitate an understanding of the various embodiments described
herein and, accordingly, may not necessarily be presented or
illustrated to scale, and are not intended to indicate any
preference or requirement for an illustrated embodiment to the
exclusion of embodiments described with reference thereto.
DETAILED DESCRIPTION
Reference will now be made in detail to representative embodiments
illustrated in the accompanying drawings. It should be understood
that the following descriptions are not intended to limit the
embodiments to one preferred embodiment. To the contrary, it is
intended to cover alternatives, modifications, and equivalents as
can be included within the spirit and scope of the described
embodiments as defined by the claims.
The embodiments disclosed herein are directed to a haptic feedback
system for use as part of an electronic device. An electronic
device transmits a signal to a user in the form of a haptic output
(e.g., a tactile output). Examples include a smart watch that
vibrates at a scheduled time, a cell phone that vibrates for an
incoming call, a tablet or other touch-sensitive computing device
that provides feedback in response to a sensed touch, a track pad
that provides haptic feedback to confirm an input, and many others.
A haptic feedback system, as described herein, includes one or more
haptic actuators for providing a haptic output, a controller for
controlling operations of the haptic actuator, and/or one or more
feedback sensors for enabling closed loop control of the haptic
actuator.
A haptic actuator generates a haptic output. Haptic actuators often
include a support mechanism (e.g., a housing or an enclosure)
attached to an electronic device, for example within a device
housing, device casing, or device enclosure, and a linear actuator
that moves a mass in varying directions; changes in momentum of the
mass are transmitted through the support mechanism to the
electronic device. In particular, linear actuators work by moving a
mass in one or both directions substantially along a single line or
axis.
The linear actuators described herein operate to produce a haptic
output by moving a mass bilinearly, that is, in both directions
along a single line. Such bilinear motion may be termed "linear
motion" and objects exhibiting such bilinear motion will be said to
be moving "linearly." Through conservation of momentum, changes in
the direction of motion of the mass are transferred to support
mechanisms of the mass. When the support mechanisms are connected
to an electronic device, either directly or through intermediate
components such as a housing or enclosure for the actuator, the
changed momentum of the mass is transferred to the electronic
device and so produces a haptic output.
Some forms of linear actuators are configured to have one or more
current carrying coils of wires that are stationary within a
housing. In those forms, a movable mass may include one or more
magnets, either permanent magnets or electromagnets. Electrical
current (e.g., alternating current, electromagnetic signals, drive
signals, and the like) induced in the current carrying coils
generates magnetic fields that in turn exert electromagnetic forces
on the magnets of the movable mass. As used herein, an
"electromagnetic force" denotes an electric force, a magnetic
force, or a combination thereof.
In contrast, some linear actuators described herein include
stationary magnetic masses (e.g., permanent magnets,
electromagnets, and the like) attached to a housing of the linear
actuator. In some embodiments, the housing defines an interior
volume. A dynamic body (e.g., movable mass, movable body) within
the interior volume of the housing is attached to one or more
conduction loops (e.g., electromagnetic coils, electrically
conductive coils, wire loops, other electrically conductive
materials, and the like). Electrical currents (e.g., alternating
current, electromagnetic signals, drive signals, and the like)
induced in the conduction loops result in a Lorentz force that can
cause the conduction coils to move, thereby causing the attached
movable mass to move. The motion of the movable body is constrained
and controlled by various mechanisms within the actuator, including
springs, elastic members, and the like, as discussed in more detail
below. As a result, the movable body oscillates within the interior
volume along a longitudinal axis of the housing.
Further, magnetic fields generated by the stationary magnets can be
oriented to pass into a housing made of a ferritic material.
Typically, but not necessarily, a ferritic material has a high
magnetic permeability. When the stationary magnets are arranged in
a linear array and adjacent magnets of the array have alternating
polarities, the magnetic flux from the permanent magnets may be
mostly confined to the housing and to shield components outside the
haptic actuator from magnetic fields. An example arrangement of
stationary magnets is a Halbach array. Further, a ferritic housing
can shield the internal components of the haptic actuator from
electromagnetic fields originating outside the haptic actuator.
When the movable mass is made, at least in part, of a ferritic
material, the magnetic fields produced by the magnets or magnetic
masses can then be channeled into the interior volume and so reduce
fringing effects of the magnetic fields. This can increase the
strength of the magnetic fields that contribute to the Lorentz
force, and so produce a stronger haptic output from less electrical
current. In one embodiment, the movable mass has a relatively thin
middle portion and thicker outside portions. This helps to minimize
the thickness of the actuator as a whole by providing space above
and below the middle portion for placement of the magnets. Further,
the thicker outside portions increase the weight of the movable
mass which allows for a stronger haptic output by the actuator.
The movable mass may be attached to the actuator housing or
enclosure by one or more elastic members to facilitate movement
(e.g., oscillation) of the mass within the enclosure (herein
"movement elastic members"). Example movement elastic members
include springs (herein "motion springs"), gels, elastomers, and
the like. In one embodiment, the motion springs are flexure
springs.
The movable mass, the conduction loop, or both may be electrically
coupled to the enclosure to facilitate transmission of electrical
current, such as electromagnetic signals and drive signals, to the
conduction loop. In one embodiment, the movable mass is
electrically coupled to the enclosure by one or more elastic
members to maintain the electrical connection between the enclosure
and the conduction loop even when the movable mass is moving within
the enclosure (herein, "conduction elastic members"). The
conduction elastic member may be a spring (herein, "contact
springs"), a gel, an elastomer, or the like. This can create or
facilitate a reliable connection between the enclosure and the
movable mass over thousands, millions, or more cycles of movement
of the movable mass. In one embodiment, the reaction force (e.g.,
spring force) of the movement elastic member is much greater than
the reaction force of the conduction elastic member, such that the
conduction elastic member does not materially influence the
dynamics of the movable mass.
The movable mass and the magnetic masses (e.g., magnets) may be
separated by a medium that allows relative motion of each. In one
embodiment, this medium is air. In another embodiment, this medium
is a fluid, which can act as a damper to help control the
oscillation of the movable mass. Additionally, some combination of
air and fluid may be used, for example fluid on one side of the
movable mass and air on another side. The fluid may be a
ferrofluid, a magnetized fluid, or similar. In embodiments where a
ferrofluid is disposed between the movable mass and one or more of
the magnets, the ferrofluid may direct magnetic flux toward the
movable mass to increase the efficiency of the haptic actuator by
requiring a smaller input signal amplitude to achieve the same
electrical current in the conduction loop. The ferrofluid also has
the advantage of being held in place by magnetic forces from the
magnet, and thus does not require additional structure or
mechanisms for containment, which allows for less overall
complexity, weight, and volume of the haptic actuator.
In one embodiment, the haptic feedback system includes a controller
electrically coupled to the haptic actuator to control operation of
the haptic actuator. The controller can include, or can be
communicably coupled to, circuitry and/or logic components, such as
a processor. The circuitry can perform or coordinate some or all of
the operations of the controller including, but not limited to:
providing a signal to a haptic actuator to generate an output;
receiving a feedback signal from a haptic actuator; generating
signals based on feedback; and so on.
The controller can be implemented as any electronic device or
component capable of processing, receiving, or transmitting data or
instructions in an analog and/or digital domain. For example, the
controller can be a processor such as a microprocessor, a central
processing unit, an application-specific integrated circuit, a
field-programmable gate array, a digital signal processor, an
analog circuit, a digital circuit, or combination of such devices.
The processor may be a single-thread or multi-thread processor. The
processor may be a single-core or multi-core processor.
Accordingly, as described herein, the phrase "controller" refers to
a hardware-implemented data processing device or circuit physically
structured to execute specific transformations of data including
data operations represented as code and/or instructions included in
a program that can be stored within and accessed from an integrated
or separate memory. The term or phrase is meant to encompass a
single processor or processing unit, multiple processors, multiple
processing units, analog or digital circuits, or other suitably
configured computing element or combination of elements.
In one embodiment, the haptic feedback system includes one or more
feedback sensors electrically coupled to the haptic actuator, the
controller, or both. Feedback signals are provided to the
controller to facilitate closed-loop control to maintain desired
haptic output.
The feedback sensors can include magnetic, mechanical, and/or
electrical sensors for determining characteristics of haptic
actuator components, including proximity, position, displacement,
velocity, acceleration, force, and the like. For example, sensors
may be used to determine the position, velocity, or acceleration of
the movable mass within the enclosure of the haptic actuator.
Example feedback sensors include capacitive sensors and Hall Effect
sensors. A capacitive sensor varies its output voltage based on
changes in capacitance, which can be used to determine the
aforementioned characteristics of haptic actuator components. A
Hall Effect sensor varies its output voltage based on changes in
magnetic field, which can be used to determine the aforementioned
characteristics of haptic actuator components.
In one embodiment, closed loop control is implemented by
determining the counter-electromotive force or back electromotive
force (herein, "back-EMF"), or the voltage generated by the motion
of the movable mass within the enclosure, which can be used to
determine the position of the movable mass at a given time.
Detailed embodiments of these general considerations will now be
disclosed in relation to the accompanying figures.
FIG. 1 illustrates an example electronic device 100 that may
incorporate a haptic feedback system according to one or more
embodiments presented herein. The electronic device 100 includes a
device casing 102, a display 104, and a user input button 106. The
device casing 102 retains, supports, and/or encloses various
components of the electronic device 100, such as a display 104. The
display 104 may include a stack of multiple layers (e.g., a display
stack) including, for example, and in no particular order: an
organic light emitting diode layer, a touch input layer, a force
input layer, and so on. Other embodiments can implement the display
104 in a different manner, such as with liquid crystal display
technology, electronic ink technology, quantum dot technology, and
so on.
The electronic device 100 can also include a processor, memory,
power supply and/or battery, network connections, sensors,
input/output ports, acoustic elements, haptic elements, digital
and/or analog circuits for performing and/or coordinating tasks of
the electronic device 100, and so on. For simplicity of
illustration, the electronic device 100 is depicted in FIG. 1A
without many of these elements, each of which may be included,
partially and/or entirely, within the device casing 102 and may be
operationally or functionally associated with, or coupled to, the
display 104 and/or the user input button 106. Output of the display
104 may vary with operation of the device, receipt of information
by the device, input received from an input mechanism (such as
button 106), output (such as may be generated by a haptic actuator
as described herein), and so on.
Furthermore, although illustrated as a cellular phone, the
electronic device 100 can be another electronic device that is
either stationary or portable, taking a larger or smaller form
factor than illustrated. For example, in certain embodiments (and
as noted above), the electronic device 100 can be a laptop
computer, a tablet computer, a wearable device, a health monitoring
device, a home or building automation device, a home or building
appliance, a craft or vehicle entertainment, control, and/or
information system, a navigation device, and so on.
FIG. 2 is a simplified system diagram depicting selected components
of a haptic feedback system 200 according to one example
embodiment. In this example, the haptic feedback system 200
includes a controller 210, an actuator 220, and a feedback sensor
230.
In various embodiments, the controller 210 receives instructions to
drive the actuator 220 to generate a haptic output from one or more
components of the electronic device. The controller 210 provides a
drive signal to drive the actuator 220. Typically, the drive signal
is a voltage signal that corresponds to a particular haptic output
that can be generated by the actuator 220.
The controller 210 receives feedback signals from the feedback
sensor 230 to facilitate closed-loop feedback to achieve a desired
haptic output. In many cases, the circuitry of the controller can
include one or more signal processing stages which can include, but
may not be limited to, amplifying stages, filtering stages,
multiplexing stages, digital-to-analog conversion stages,
analog-to-digital conversion stages, comparison stages, feedback
stages, charge amplification stages, and so on. The controller 210
may be integrated with components of the electronic device,
including, for example, the processor, memory, power supply, and so
on.
The actuator 220 produces a haptic output based on electrical
current (e.g., in the form of drive signals, electromagnetic
signals, and the like) received from the controller 210. The
actuator 220 may be a linear actuator (such as a linear resonance
actuator) that produces a haptic output by linear motion of a mass.
The actuator 220 includes an enclosure or housing, one or more
magnetic masses (e.g., magnets), and a movable mass that includes a
conduction loop (e.g., a wire loop, wound coil, and the like).
The feedback sensor 230 provides feedback signals to the controller
210. Feedback signals can be used by the controller 210 to
determine characteristics of the actuator 220 to facilitate
closed-loop control to produce a desired haptic output.
Characteristics include the position and/or velocity of the movable
mass within the enclosure. As an example, consider a situation in
which the desired haptic output is consistent with linear motion of
the movable mass (i.e., motion along an axis in an x-direction
only). The controller 210 may determine from feedback data received
by the feedback sensor 230 that there is motion in the y- and/or
z-direction that is not consistent with the desired haptic output.
In one embodiment, the controller 210 compares expected values for
the feedback data to the received feedback data. As a result of
this determination the controller 210 may adjust the drive signal
(e.g., generate a corrective signal) to correct the unwanted motion
and achieve the desired haptic output.
The feedback sensor 230 may include one or more sensors, such as
capacitive sensors for measuring changes in capacitance of
components of the actuator 220, and/or Hall Effect sensors for
measuring changes in a magnetic field of the actuator 220. The
feedback sensor 230 may consist of multiple sensors at different
locations within and around the actuator 220. The feedback sensor
230 may be integrated with the controller 210, for example as a
circuit, processor, algorithm, or the like (e.g., a back
electromotive force sensor) configured to determine a back-EMF of
the actuator 220, or the voltage generated by the motion of the
movable mass within the enclosure, which can be used to determine
the position of the movable mass at a given time.
In some embodiments, the haptic feedback system 200 does not
include feedback sensors 230. In this embodiment, the controller
210 and the actuator 220 operate in open-loop mode, as opposed to
closed-loop or feedback control mode. In this embodiment, the
controller 210 generates a desired signal or waveform to produce a
haptic output, and the actuator 220 produces the haptic output in
response to receiving the desired waveform from the controller.
The actuator 220, the feedback sensor 230, and the components and
structure of each are discussed in more detail below with respect
to FIGS. 3A-8D.
FIG. 3A depicts an example construction of a haptic actuator 300,
such as described herein. The haptic actuator 300 includes an
enclosure 301. In various embodiments, the enclosure 301 is a
substantially rectangular housing comprised of a durable material
(e.g., stainless steel, titanium, aluminum or other suitable
metals, ceramic, certain polymers, and the like). The enclosure 301
may consist of multiple parts, such as a base and a crust, which
fit together to form an interior volume within the enclosure. The
enclosure 301 may include one or more openings, for example for
power delivery components. The enclosure 301 may further include
attachment mechanisms for attaching or otherwise integrating the
enclosure into the electronic device 100, for example within the
device casing 102. Further, the enclosure 301 may include various
components that are not pictured in the figures, including
electrical transmission components such as flex cables for
transmitting signals within the enclosure. The enclosure 301 may
further include motion control components, such as stoppers, bump
guards, and the like. The motion control components may be used to
protect components of the actuator 300 from damage based on the
motion within the actuator.
FIG. 3B is a cross-section of the haptic actuator 300, taken
through section line A-A of FIG. 3A. The haptic actuator 300
includes a dynamic body 310, a conduction loop 320, movement
elastic members 330A-B, conduction elastic members 340A-B, and one
or more magnets (not pictured in FIG. 3B). FIG. 3C is a
cross-section of the haptic actuator 300, taken through section
line B-B of FIG. 3B. FIG. 3C illustrates magnets 350A-B.
The dynamic body 310 is disposed in the interior volume of the
enclosure 301 and mechanically coupled to the enclosure 301 by
movement elastic members 330, and electrically coupled to the
enclosure 301 by conduction elastic members 340. The dynamic body
310 may be made of a high-density material (e.g., greater than 15
grams per cubic centimeter) to maximize the momentum of the mass
and thus the strength of the haptic feedback during motion of the
actuator. In one embodiment, the dynamic body 310 is made of
tungsten.
The conduction loop 320 is coupled (e.g., affixed) to the dynamic
body 310 and is electrically coupled to the conduction elastic
members 340. The conduction loop 320 may be made of any suitable
conductive material that can be energized by an electrical current
(e.g., a drive signal or other electromagnetic signal), thereby
generating a Lorentz force to cause the dynamic body to move along
the longitudinal axis of the enclosure 301 (e.g., the left-to-right
and right-to-left directions in FIG. 3B). In one embodiment, the
conduction loop 320 is a substantially round loop made of round
wire (e.g., copper wire). In another embodiment, as illustrated in
FIG. 3B, the conduction loop 320 is an electromagnetic coil that
has a rounded-rectangular shape and is made of square or
rectangular wire. The conduction loop 320 may extend near or beyond
the border of the dynamic body 310. This maximizes the Lorentz
force by increasing the strength of the magnetic field generated by
the conduction loop 320.
The movement elastic members 330 are elastic members that allow
movement of the dynamic body 310 relative to the enclosure 301 and
the magnets 350 along a longitudinal axis of the enclosure 301. In
the example of FIG. 3B, two movement elastic members 330A-B are
shown, but more or fewer movement elastic members may be used in
various embodiments. The movement elastic members 330 may be
springs, gels, elastomers, or the like made of any suitable elastic
material. In one embodiment, the movement elastic members 330 are
metal springs (e.g., flexure springs, leaf springs, coil springs,
and the like) with a high strength-to-weight ratio such as
stainless steel. The movement elastic members 330A-B may be
positioned on opposite sides of the longitudinal axis of the
enclosure 301 from one another, as illustrated in FIG. 3B. This
minimizes movement of the dynamic body 310 in directions other than
along the longitudinal axis. For example, the movement elastic
members 330 may be connected to or otherwise constrained by the
dynamic body 310 at connection locations (e.g., connection points,
connection areas) as shown in FIG. 3B. The connection location of
movement elastic member 330A may be offset from the longitudinal
axis in one direction, and the connection location of the movement
elastic member 330B may be offset from the longitudinal axis in
another direction.
The conduction elastic members 340 are elastic members that allow
for electrical current (e.g., drive signals, electromagnetic
signals, and the like) to be transmitted to the conduction loop 320
while the dynamic body 310 is stationary and during movement. As
the dynamic body 310 moves within the enclosure 301, the conduction
elastic members 340 maintain an electrical connection with both the
enclosure 301 and the conduction loop 320. The conduction elastic
members 340 may be made of any suitable elastic and conductive
material, such as a spring, a doped gel, an elastomer, and the
like. In various embodiments, the conduction elastic members 340
are springs (e.g., flexure springs, leaf springs, coil springs, and
the like) with relatively high electrical conductivity and yield
strength (e.g., Cu-2Ag wire, Cu-4Ag wire, and the like). The
conductivity allows for proper transmission of electrical current,
including electromagnetic signals, to the conduction loop 320, and
the high yield strength allows the conduction elastic members 340
to maintain elasticity over thousands, millions, or more
compression and stretching events. The conduction elastic members
340 change shape (e.g., expand and contract, deflect, and the like)
as the dynamic body 310 moves within the interior volume of the
enclosure, thereby maintaining the electrical connection between
the conduction loop 320 and the controller. Similar to the movement
elastic members 330, the conduction elastic members 340A-B may be
positioned on opposite sides of the longitudinal axis of the
enclosure 301 from one another, as illustrated in FIG. 3B. For
example, the conduction elastic members 340 may be connected to or
otherwise constrained by the dynamic body 310 at connection
locations (e.g., connection points, connection areas) as shown in
FIG. 3B. The connection location of conduction elastic member 340A
may be offset from the longitudinal axis in one direction, and the
connection location of the conduction elastic member 340B may be
offset from the longitudinal axis in another direction. As shown in
FIG. 3B, the conduction elastic members 340 may be positioned
relative to the movement elastic members 330 such that the elastic
members on the same side of the dynamic body 310 (e.g., movement
elastic member 330A and conduction elastic member 340A) are located
on opposite sides of the longitudinal axis. For example, the
movement elastic member 330A may be offset from the longitudinal
axis in one direction and the conduction elastic member 340A may be
offset from the longitudinal axis in another direction.
In one embodiment, the reaction force (e.g., spring force) of the
movement elastic members 330 is significantly greater than the
reaction force of the conduction elastic members 340. For example,
the reaction force of the movement elastic members 330 may be
approximately 0.5-3 N/mm, and the reaction force of the conduction
elastic members 340 may be approximately 0.001-0.01 N/mm. As a
result, the effect of the conduction elastic members 340 on the
movement of the dynamic body 310 is negligible compared to the
effect of the movement elastic members 330.
The magnets 350 are coupled to the enclosure 301 and generate a
magnetic field within the interior volume of the enclosure 301. The
magnetic field results in a Lorentz force on the conduction loops
320 that causes the dynamic body 310 to move within the interior
volume of the enclosure 301. The magnets 350 may be any suitable
magnetic mass, such as permanent magnets, electromagnets, or the
like. In various embodiments, the magnets 350 are arranged in
planar arrays in which adjacent magnets have alternating
polarities. This causes the magnetic flux to be augmented on one
side and reduced on another, and can be used to confine the
magnetic flux within the interior volume of the enclosure 301 to
avoid interactions with other components of the electronic device.
Example magnetic arrays are discussed in more detail below with
respect to FIGS. 5A-F.
In operation, the actuator 300 receives an input signal (e.g., a
drive signal, electromagnetic signal, or other electrical current)
from a controller of the electronic device and generates a haptic
output. The controller is electrically coupled to the conduction
elastic members 340, for example by a flex cable partially or
entirely within the enclosure 301. The conduction elastic members
340 convey the input signal to the conduction loop 320. The signal
energizes the conduction loop 320, which generates a magnetic
field. The interaction of this magnetic field with the magnets 350
causes a force on the conduction loop 320, and thereby the dynamic
body 310, along an x-axis or longitudinal axis (left-to-right with
reference to FIGS. 3B and 3C). This force causes the dynamic body
310 to move along the longitudinal axis ("linear motion"). The
movement elastic members 330 constrain the movement of the dynamic
body 310 by imparting a reaction force (e.g., spring force) on the
dynamic body 310. This causes the dynamic body 310 to oscillate
along the longitudinal axis within the enclosure 301. The movement
of the dynamic body 310 within the enclosure 301 results in a
haptic output that can be felt by a user of the electronic
device.
Movement of the dynamic body 310 in directions other than along the
longitudinal axis is possible, but in general not desired. This is
because such movement results in wasted energy, thereby reducing
the efficiency of the actuator 300. Additionally, such movement can
cause the dynamic body 310 to contact the enclosure 301 and other
components of the actuator 300, resulting in damage, unwanted
noise, interference with haptic outputs, and the like. Various
aspects of the actuator 300 constrain movement in the y-direction
(top-to-bottom with reference to FIG. 3B), the z-direction
(top-to-bottom with reference to FIG. 3C), or some combination of
the x-, y-, and z-directions (e.g., twisting or rolling). Movement
in the y- and z-directions, including translation, twisting, and
rolling, is constrained by the presence of the movement elastic
members on opposite sides of the longitudinal axis of the dynamic
body 310. Movement in the y-direction is additionally constrained
by the relative positions of the movement elastic members 330A and
330B, for example diagonally across from one another as illustrated
in FIG. 3B. This positioning generally minimizes y-direction
movement, including situations in which the dynamic body 310
contacts the enclosure 301. Movement in the z-direction may be
constrained by a viscous fluid damper between the dynamic body 310
and one or more of the magnets 350, as discussed in more detail
below with respect to FIGS. 4A-4C. Additionally, physical
mechanisms may constrain the movement of the dynamic body 310 in
any direction. For example, stops made of an elastic material
(e.g., rubber, silicone, and the like) may be placed within the
enclosure to constrain movement. In another embodiment, the
enclosure 301 may include one or more shafts (not pictured) that
constrain the movement of the dynamic body 310. For example, the
dynamic body 310 may be disposed around a shaft that causes the
dynamic body 310 to move in the x-direction. Alternatively or
additionally, one or more shafts within the enclosure 301 may guide
or restrict the motion of the dynamic body 310.
FIG. 4A depicts a second example construction of a haptic actuator,
such as described herein. The haptic actuator 400 of FIG. 4A
includes an enclosure 401 that defines an interior volume. FIG. 4B
is a cross-section of the haptic actuator 400, taken through
section line C-C of FIG. 4A. The haptic actuator 400 includes a
movable body 410 (similar to the dynamic body 310 of FIGS. 3A-3C),
electromagnetic coils 420A-B, motion springs 430A-B, contact
springs 440A-B, and one or more magnets (not pictured in FIG. 4B).
FIG. 4C is a cross-section of the haptic actuator 400, taken
through section line D-D of FIG. 4B. FIG. 4C illustrates magnets
450A-B.
The haptic actuator 400 is similar to the haptic actuator 300
discussed above with respect to FIGS. 3A-3C. In addition to the
features and characteristics of the haptic actuator 300, the haptic
actuator 400 includes various additions and variations. The
electromagnetic coils 420A-B are rounded rectangular coils that are
made of rectangular or square wire of any suitable conductive
material (e.g., copper, nickel, gold, and the like). As used
herein, the term "rounded rectangular" or "rounded rectangle"
refers to a shape with straight sides and rounded corners. The
rectangular coils and rectangular wire of the electromagnetic coils
420 allow for more material to fit in a smaller space, thereby
helping to minimize the size of the actuator 400. The
electromagnetic coils 420 may be oriented within the enclosure 401
parallel to the magnets 450A-B.
The movable body 410 includes an inner portion that is relatively
thin compared to outer portions, as illustrated in FIG. 4C. The
inner portion is relatively thin so that it may be positioned
between the magnets 450 while minimizing the thickness of the
actuator 400. The outer portions are thicker to add weight to the
movable body 410, the movement of which creates a stronger haptic
output.
The motion springs 430 are flexure springs and are positioned in
opposite orientations to minimize non-linear motion of the movable
body 410. The flexure springs have a general wishbone shape and
flex during compression and stretching. Flexure springs provide
several advantages for the actuator 400. First, flexure springs
have a high spring constant for a relatively small distance between
the ends of the spring. This allows the springs to take up less
space within the enclosure 401, and in particular along the
actuation axis, as illustrated in FIG. 4B, thereby helping to
minimize the size of the actuator 400. Further, the flexure springs
help to minimize the non-linear motion of the movable body 410
because they are relatively rigid in the y- and z-directions. As
discussed above with respect to FIGS. 3A-3C, minimizing non-linear
motion is advantageous for the efficiency and operation of the
actuator 400.
The contact springs 440 are coiled wire springs with a "beehive"
shape (i.e., the center of the spring is wider than the ends). This
concentrates the peak stress at the center of the coil and away
from the connections (e.g., solder joints) with the enclosure 401.
As a result, potential failures along the connections are
mitigated, leading to increased lifespan and reliability of the
actuator 400. In one embodiment, the diameter of the spring is
small (e.g., approximately 50 micrometers) to minimize the spiral
spring torsion force applied to the mass by the contact springs
440. This minimizes the unwanted movement of the movable body 410
discussed above. Similarly, each of the two contact springs 440A
and 440B may have opposing coil directions to offset the spiral
spring tension force. The contact springs 440 are constructed from
a material with high conductivity for providing signals to the
electromagnetic coils 420, and high yield strength to avoid failure
of the springs as a result of fatigue. Example materials include
copper-silver wire (e.g., CU-2Ag or CU-4Ag), annealed or rolled HA
copper foil, TPC wire, C7024-XSH foil, NKC388-USH strip, C7035-XV
foil, NKT322-ESH strip, C1990-GSH foil, BF 158 strip or foil,
electroformed Co--P, and Cu-0.3% Sn.
The contact springs 440 are connected to the enclosure by contacts
445A and 445B. The contacts 445 additionally constrain the movement
of the contact springs 440 by opposing the spring force of the
contact springs. In one embodiment, as illustrated in FIG. 4B, a
contact 445 constrains the movement of a contact spring 440 by
constraining an end of the contact spring. In various embodiments,
the contacts 445 are rigid members that are electrically connected
to the controller, for example by flex cables or the like.
The haptic actuator 400 additionally includes fluid 460 that acts
as a damper to help control the movement of the movable body 410.
In one embodiment, the fluid 460 is a magnetized fluid or
ferrofluid. In this embodiment, the fluid 460 may direct magnetic
flux toward the movable body 410 to increase the efficiency of the
haptic actuator 400 by requiring a smaller input signal amplitude
to achieve the same electrical current in the electromagnetic coils
420. The ferrofluid also has the advantage of being held in place
by magnetic forces from the magnet, and thus does not require
additional structure or mechanisms for containment, which allows
for less overall complexity, weight, and volume of the haptic
actuator 400. The fluid 460 dampens linear movement of the movable
body 410 to improve the control of the linear movement. For
example, the fluid 460 allows faster attenuation of oscillation,
which makes possible shorter haptic output events that are more
noticeable to users. Further, the fluid 460 may dampen movement in
the y- and z-directions as discussed above with respect to FIGS.
3A-3C, which improves the function and reliability of the actuator
400.
FIGS. 5A-5F depict example configurations for magnet arrays in
haptic actuators, such as those described herein. FIG. 5A depicts a
top view of an example Halbach array 510A. FIG. 5A includes magnets
515A-E, which have differing magnetic field directions as
illustrated by the indicators. FIG. 5B depicts a side view of the
Halbach array of FIG. 5A. FIG. 5B also depicts the differing
magnetic field directions of the adjacent magnets. The result of
the arrangement of the magnets in FIGS. 5A and 5B is a decreased
magnetic flux on the top of the array, and an increased magnetic
flux on the bottom of the array. A similar array may be used as the
magnets described herein to direct magnetic flux toward the
conduction loops or electromagnetic coils of the haptic
actuator.
FIG. 5C depicts a top view of a second example Halbach array 510C.
The Halbach array 510C is similar to the Halbach array 510A. The
Halbach array of FIG. 5C includes different sized magnets, such as
magnets 515F and 515G. This has an advantage of saving space,
thereby reducing the overall size of the actuator. The Halbach
array 510C includes additional magnets, such as 516A and 516B on
the sides of the magnets 515 to further augment the magnetic flux.
The Halbach array 510C additionally includes spacers 520 to further
direct the magnetic field. In one embodiment, the spacers are a
non-ferrous material (e.g., aluminum). In another embodiment, the
spacers are magnetic.
FIG. 5D depicts a top view of a third example Halbach array 510D.
The Halbach array 510D is similar to the Halbach array 510C, but
the smaller magnets 515 (such as 515H and 515I) extend between the
magnets 516, so spacers are not needed. This has the advantage of
reducing the complexity and number of components of the Halbach
array 510D as compared to, for example, the Halbach array 510C.
FIG. 5E depicts a top view of a fourth example Halbach array 510E.
The Halbach array 510E is similar to the Halbach arrays 510C and
510D, and includes magnets 515, such as 515J and 515K, and magnets
516, such as magnets 516E and 516F. The Halbach array 510E
additionally includes magnets 517A and B, which are loop magnets
which have magnetic fields in the direction away from the center of
the loop. The loop magnets 517 function similarly to the separate
magnets 515 and 516, but this configuration has the advantage of
reducing the number of components of the Halbach array compared to
arrays 510C and 510D.
FIG. 5F depicts a side view of a fifth example Halbach array 510F.
The Halbach array 510F includes magnets 518A-E with alternating
magnetic field directions similar to magnets 515A-E of FIG. 5B.
Magnets 518A-E have triangular cross-sections, which further
increases the augmentation effect on the magnetic flux compared to
arrays 510A-E. FIG. 5G depicts a side view of a sixth example
Halbach array 510G. The Halbach array 510G includes magnets 519A-E
with alternating magnetic field directions similar to magnets
515A-E of FIG. 5B. Magnets 519A-E have trapezoidal cross-sections,
which, similar to array 510F, further increases the augmentation
effect on the magnetic flux compared to arrays 510A-E. FIG. 5H
depicts a side view of a sixth example Halbach array 510H. The
Halbach array 510H includes magnets 520A-E with alternating
magnetic field directions similar to magnets 515A-E of FIG. 5B.
Magnets 520A-E have trapezoidal or triangular cross-sections
similar to the magnets of arrays 510F and 510G. Similar to arrays
510F and 510G, the cross-section shapes further increase the
augmentation effect on the magnetic flux compared to arrays 510A-E.
The magnets described above with respect to FIGS. 5A-5H may be any
suitable magnetic mass, such as electromagnets, permanent magnets,
temporary magnets, and the like.
FIGS. 6A-6C depict an example configuration of capacitive sensors
within a haptic actuator, such as described herein. In the example
of FIGS. 6A-6C, movable body 620 moves within enclosure 600 from a
first position (FIG. 6A) to a second position (FIG. 6B) to a third
position (FIG. 6C). The first position may be, for example, a
neutral position of the movable body 620 prior to a signal being
provided to generate a haptic output or a position during movement
(e.g., oscillation) of the movable body 620. The second position is
a leftward position during movement of the movable body 620. The
third position is a rightward position during movement of the
movable body 620. Capacitive sensors 610A-B and 615A-B detect
changes in capacitance based on the position or motion of the
movable body 620, which can be used to determine a relative
position of the movable body 620 within the enclosure. In various
embodiments, the movable body 620 acts as a capacitive plate, the
motion of which results in changes in the sensed capacitance by the
capacitive sensors 610 and 615. In the example of FIGS. 6A-6C, four
capacitive sensors 610, 615 are employed, but in other embodiments,
more or fewer sensors may be employed
Capacitive sensors 610 are configured to measure the position of
the movable body 620 in the z-direction (into and out of the page
with reference to FIGS. 6A-6C). During motion of the movable body
620, the movable body continuously covers capacitive sensors 610.
As a result, the x-position (left and right with reference to FIGS.
6A-6C) of the movable body does not affect the capacitance detected
by the capacitive sensors 610. Accordingly, any changes in
capacitance detected by the capacitive sensors 610 can be
attributed to changes in the z-position of the movable body 620.
Additionally, because there are two capacitive sensors 610A and
610B for measuring the z-position, differences in the readings can
be used to determine roll (e.g., the top edge in FIG. 6A is higher
or lower than the bottom edge), pitch (e.g., the left edge in FIG.
6A is higher or lower than the right edge), and combinations
thereof. This information can be relayed to the controller to
adjust the signals sent to the actuator to mitigate non-linear
movement.
Capacitive sensors 615 are configured to measure (e.g., determine)
the position of the movable body 620 in the x-direction (left and
right with reference to FIGS. 6A-6C). During motion of the movable
body 620, the border of the movable body moves over the capacitive
sensors 615. As a result, the x-position of the movable body 620
changes the capacitance detected by sensors 615. Accordingly,
changes in capacitance can be attributed to changes in the
x-position of the movable body 620. In various embodiments, the
z-position changes measured by sensors 610 can be factored into the
measurements by the sensors 615 to more accurately determine the
x-position of the movable body 620. Similar to above, differences
in the readings between the two capacitive sensors 615A and 615B
can be used to determine pitch, roll and combinations thereof.
For example, the measured capacitance of each of the four
capacitive sensors 610 will be different between FIGS. 6A and 6B
based on the position of the movable body 620. Using four
capacitive sensors 610 allows for determination of the position of
the movable body in the x-direction (left to right in FIG. 6A),
movement in the y- and z-directions, as well as "roll" (i.e.,
deviation from the plane) of the movable body 620.
FIGS. 7A-7C depict an example configuration of magnetic sensors
within a haptic actuator such as those described herein. In the
example of FIGS. 7A-7C, movable mass 720 moves within an enclosure
from a first position (FIG. 7A) to a second position (FIG. 7B) to a
third position (FIG. 7C). The first position may be, for example, a
neutral position of the movable mass 720 prior to a signal being
provided to generate a haptic output or a position during movement
(e.g., oscillation) of the movable mass 720. The second position is
a rightward position during compression of a spring 730 during
oscillation of the movable mass 720. The third position is a
leftward position during compression of a spring 730 during
oscillation of the movable mass 720.
Magnets 740, 741 are coupled to the movable mass 720 such that they
move with the movable mass. The magnets 740 may be permanent
magnets, electromagnets, or the like. In the example of FIGS.
7A-7C, two magnets 740 are shown, but more or fewer magnets may be
used. The magnets 740, 741 may be attached to and/or protrude
(partially or entirely) from an edge of the movable mass 720 as
illustrated by magnets 740A, 741A in FIG. 7A. The magnets 740, 741
may also be attached to or otherwise disposed within the movable
mass 720 such that the surface of the magnets is flush with the
surface of the movable mass 720, as illustrated by magnets 740B,
741B in FIG. 7B. The magnets 740 may be dipole magnets oriented
opposite each other to create differing magnetic fields that can be
detected by the Hall Effect sensors 750. For example, with
reference to FIGS. 7A-7C, magnet 740A may be oriented with a north
pole facing down while magnet 740B may be oriented with a south
pole facing down such that the magnetic flux around each is
different and capable of detection and differentiation.
Hall Effect sensors 750, 751 are coupled to a surface of a wall 702
within the enclosure of the haptic actuator such that the movable
mass 720 and the magnets 740 move relative to the sensors 750. The
Hall Effect sensors 750 detect changes in magnetic flux caused by
movement of the magnets 740. These detected changes can be used to
determine the position of the movable mass 720. In one embodiment,
as shown in FIGS. 7A-7C, sensor 750 is located under the magnet 740
such that the magnet 740 is always above the sensor 750, even
during motion of the movable mass 720. In this configuration, the
sensor 750 primarily detects the magnetic flux of the magnet 740
and the effects of the magnet 741 are negligible. Accordingly, the
motion of the movable mass 720 in the x-direction (left to right
with reference to FIGS. 7A-7C) does not materially affect the
magnetic flux detected by the sensor 750. As a result, changes in
magnetic flux detected by the sensor 750 can be attributed to
changes in the z-position (up and down with reference to FIGS.
7A-7C) of the movable mass 720. In contrast, as shown in FIGS.
7A-7C, the sensor 751 is positioned such that it may be under
magnet 740, magnet 741, or both depending on the x-position of the
movable mass 720. Because the magnets 740, 741 have different
magnetic flux than one another, the flux detected by the sensor 751
can be used to determine the x-position of the movable mass 720. In
various embodiments, the z-position determined by the sensor 750
may be used to adjust the reading by the sensor 751 for a more
accurate determination of the x-position.
Referring to FIG. 7A, sensors 750, 751 may be attached to and/or
protrude (partially or entirely) from a surface of the enclosure
wall 702A as illustrated by sensors 750A, 751A. Referring to FIG.
7B, sensors 750, 751 may be attached to or otherwise disposed
within the enclosure wall 702B such that the surface of each sensor
is flush with the surface of the enclosure wall 702B, as
illustrated by sensors 750B, 751B. Referring to FIG. 7C, sensors
750, 751 may be disposed within a recessed area of the enclosure
wall 702C as illustrated by sensors 750C, 751C.
In the example of FIGS. 7A-7C, Hall Effect sensors are used to
measure changes in the magnetic field. In various embodiments,
different types of sensors may be used in place of the sensors
discussed above, including anisotropic magnetoresistance (AMR)
sensors, giant magnetoresistance (GMR) sensors, and tunneling
magnetoresistance (TMR) sensors.
FIG. 8A-8C are cross-sections similar showing portions of example
haptic actuators, such as those described herein. FIG. 8A is a
cross-section of a first example haptic actuator 800A. The haptic
actuator 800A includes an enclosure 801A, a dynamic body 810A, a
conduction coil 820A, a motion spring 830A, a contact spring 840A,
and an electrical contact 845A. The haptic actuator 800A is similar
in form and function to the haptic actuator 400 of FIGS. 4A-C, but
the haptic actuator 800A has one motion spring 830A and one contact
spring 840A instead of two. FIG. 8B is a cross-section of a second
example haptic actuator 800B. The haptic actuator 800B includes a
movement elastic member 830B, which is a flexure spring that is
attached at a bottom edge of the dynamic body 810B. The attachment
of the flexure spring to various surfaces of dynamic body 810B is
envisioned. Additionally, the conduction elastic member 840B is a
c-shaped elastic member such as a leaf spring. Various forms of
elastic members and combinations thereof for the movement elastic
members and the conduction elastic members are envisioned. Further,
as illustrated in FIGS. 8A-8C, the conduction elastic member 840B
may be attached to the contact 845B at various locations. FIG. 8C
is a cross-section of a second example haptic actuator 800C. The
haptic actuator 800C includes a motion spring 830C, which is a
c-shaped spring such as a leaf spring that is attached at a bottom
edge of the dynamic body 810C. Additionally, the contact spring
840C is a c-shaped elastic member such as a leaf spring.
FIG. 9 is a simplified flow chart depicting example operations of a
haptic feedback system, such as described herein. The method 900
includes operation 910 in which a controller receives an
instruction to provide haptic feedback, for example using a haptic
actuator of an electronic device. Next, at operation 920, the
controller sends a signal to an actuator (e.g., a haptic actuator)
that causes the actuator to output haptic feedback. Then, at
operation 930, the controller receives feedback from a feedback
sensor associated with the actuator, which may be used to
facilitate closed-loop control of the actuator.
As noted above, many embodiments described herein reference a
haptic feedback system operated in conjunction with a portable
electronic device. It may be appreciated, however, that this is
merely one example; other configurations, implementations, and
constructions are contemplated in view of the various principles
and methods of operation--and reasonable alternatives
thereto--described in reference to the embodiments described
above.
For example, without limitation, a haptic feedback system can be
additionally or alternatively associated with: a display surface, a
housing or enclosure surface, a planar surface, a curved surface,
an electrically conductive surface, an electrically insulating
surface, a rigid surface, a flexible surface, a key cap surface, a
trackpad surface, a display surface, and so on. The interface
surface can be a front surface, a back surface, a sidewall surface,
or any suitable surface of an electronic device or electronic
device accessory. Typically, the interface surface of a multimode
force interface is an exterior surface of the associated portable
electronic device but this may not be required.
Further, although many embodiments reference a haptic feedback
system in a portable electronic device (such as a cell phone or
tablet computer) it may be appreciated that a haptic feedback
system can be incorporated into any suitable electronic device,
system, or accessory including but not limited to: portable
electronic devices (e.g., battery-powered, wirelessly-powered
devices, tethered devices, and so on); stationary electronic
devices; control devices (e.g., home automation devices, industrial
automation devices, aeronautical or terrestrial vehicle control
devices, and so on); personal computing devices (e.g., cellular
devices, tablet devices, laptop devices, desktop devices, and so
on); wearable devices (e.g., implanted devices, wrist-worn devices,
eyeglass devices, and so on); accessory devices (e.g., protective
covers such as keyboard covers for tablet computers, stylus input
devices, charging devices, and so on); and so on.
Although specific electronic devices are shown in the figures and
described herein, the haptic actuators described herein may be used
with various electronic devices, mechanical devices,
electromechanical devices and so on. Examples of such include, but
are not limited to, mobile phones, personal digital assistants,
time keeping devices, health monitoring devices, wearable
electronic devices, input devices (e.g., a stylus, trackpads,
buttons, switches, and so on), a desktop computer, electronic
glasses, steering wheels, dashboards, bands for a wearable
electronic device, and so on. Although various electronic devices
are mentioned, the haptic actuators and linear actuators disclosed
herein may also be used in conjunction with other products and
combined with various materials.
One may appreciate that although many embodiments are disclosed
above, that the operations and steps presented with respect to
methods and techniques described herein are meant as exemplary and
accordingly are not exhaustive. One may further appreciate that
alternate step order or fewer or additional operations may be
required or desired for particular embodiments.
Although the disclosure above is described in terms of various
exemplary embodiments and implementations, it should be understood
that the various features, aspects and functionality described in
one or more of the individual embodiments are not limited in their
applicability to the particular embodiment with which they are
described, but instead can be applied, alone or in various
combinations, to one or more of the some embodiments of the
invention, whether or not such embodiments are described and
whether or not such features are presented as being a part of a
described embodiment. Thus, the breadth and scope of the present
invention should not be limited by any of the above-described
exemplary embodiments but is instead defined by the claims herein
presented.
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